The way to remove it is:
Modify cakelibsviewtemplateslayoutsdefault.thtml, which is a general template framework for view files (with header and footer).
In addition:
The extensions of cakephp view files are all thtml. This is the default value. If you want to modify the suffix name, you can also change it.
The modification method is:
Change var $ext='.thtml' to html in cakelibscontrollercontroller.php.